NSW Water Quality and River Flow Objectives About the Objectives Department of Environment, Climate Change and Water   Select from the scrolling list, statewide map or catchment list Select a catchment Barwon-Darling and Far Western Bega River Bellinger River Border Rivers Brunswick River Camden Haven and Hastings River Castlereagh River Clarence River Clyde River and Jervis Bay Cooks River Georges River Gosford and Northern Beaches Lagoons Gwydir River Hacking River Hawkesbury-Nepean River Hunter River Karuah River and Great Lakes Lachlan River Illawarra Lake Macquarie and Tuggerah Lakes Macleay River Macquarie-Bogan River Manning River Moruya River Murray River Murrumbidgee River and Lake George Nambucca River Namoi River Richmond River Shoalhaven River Sydney Harbour and Parramatta River Towamba and Genoa River Tuross River Tweed River Williams River

Barwon-Darling and Far Western
River Flow Objectives explained

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• Recommending variations to objectives
• Interstate processes
• Environmental flow rules for regulated rivers
• Protect pools in dry times
• Protect natural low flows
• Protect important rises in water levels
• Maintain wetland and floodplain inundation
• Mimic natural drying in temporary waterways
• Maintain natural flow variability
• Maintain natural rates of change in water levels
• Manage groundwater for ecosystems
• Minimise effects of weirs and other structures
• Minimise effects of dams on water quality
• Make water available for unforeseen events

This section explains each of the River Flow Objectives (RFOs). See the RFOs for each part of the Barwon-Darling and Far Western catchments, except regulated streams.

This section does NOT apply to the Barwon-Darling River, within the river floodplain marked on the map in brown. It also does not apply to streams in areas subject to interstate processes, including the Lower Darling, Narran and Culgoa rivers (in areas marked in pink).

In total, there are eleven inland interim River Flow Objectives, each dealing with a critical element of natural river flows.

Flow patterns in many rivers have been significantly altered and will not return to natural flow regimes. The NSW Government is not attempting to restore completely natural flow patterns where the community significantly benefits from altered flow patterns. Communities and the Government have identified important areas where we can make adjustments to maintain or improve river health while continuing to benefit from water use.

Water Sharing Plans (WSPs) play a critical role in achieving RFOs or working towards achieving them over time. WSPs can help to achieve RFOs by establishing environmental water provisions, flow classess that manage pumping in unregulated rivers, as well as release and operation rules for dams and other infrastructure. The State Water Management Outcomes Plan (SWMOP) also guides implementation of RFOs and sets out the Government’s priorities.

Recommending variations to objectives

The Natural Resources Commission (NRC) will review the role of Water Sharing Plans in achieving state-wide natural resource management standards and targets after 5 years of the plan being made. As part of this review the NRC will call for public submissions and consider other state-wide policies or agreements that are relevant to the catchment management area. The Minister for Natural Resources will consider the review undertaken by the NRC when deciding whether to extend the duration of the current water sharing plan or to make a replacement plan.

The Minister may also amend a WSP if the plan so allows (for example a review of access provisions after a specified timeframe or after a study on environmental, economic and social impacts has been carried out).

Interstate processes

Two areas of the Barwon-Darling and Far Western catchments are subject to interstate processes.

Culgoa, Birrie, Bokhara and Narran rivers
These rivers within the Barwon-Darling and Far Western Catchments depend on flows from the Condamine and Balonne rivers in Queensland. The Queensland Government has established a Water Resource Plan for this catchment. The NSW Government has not recommended River Flow Objectives for the Culgoa-Narran area at this stage, but Water Quality Objectives are established for these streams.

Objectives for river flow, as well as for water quality, are recommended for the NSW parts of other streams intersected by the state border, such as the Paroo River. The Queensland Government has established Water Resource Plans for the Queensland parts of these catchments.

In the south, the Lower Darling River below Lake Wetherell is managed in association with the Murray River to contribute to the water needs of NSW, Victoria and South Australia. The involvement of all three states is therefore required in the setting of objectives. The Murray-Darling Basin Commission is managing the process of setting both river flow and Water Quality Objectives, taking into account community input. Interim objectives for these streams are therefore not recommended.

Environmental flow rules for regulated rivers

River Flow Objectives were not recommended for the regulated parts of the Murray, Murrumbidgee, Lachlan, Macquarie, Namoi, Gwydir and Hunter Rivers, as well as for the Barwon-Darling River. This is because as part of water reforms, in 1998 the Government established Environmental Flow Rules for these rivers, after consideration by River Management Committees. These flow rules considered the principles of the River Flow Objectives and generally applied from 1998 until 2004.

River Management Committees developed Water Sharing Plans for the regulated rivers, which were commenced by the Minister for Natural Resources in July 2004. These Plans contain updated environmental flow rules, which are generally based on the principles of the River Flow Objectives, consistent with the State Water Management Outcomes Plan.

For the Barwon-Darling River, the Environmental Flow Rules still apply. In September 2005, the Minister for Natural Resources announced that a Water Sharing Plan for the Barwon-Darling will be developed. This will include protection of low flows and downstream flow targets. The community will be involved in developing the WSP.

During dry times, some streams stop flowing and form pools. Pools and wetlands are refuges for aquatic plants and animals. Pumping water from them can make it more difficult for many species to recover after a drought.

Measures to achieve objective

• There should be no water extraction from streams or wetlands in periods of no flow.
• If conditions on water licences do not provide for this objective to be met, priority should be given to implementing it by actions appropriate to local circumstances.

Supporting information

• WSPs should define when and how to protect specific pools:
• in natural wetlands with licensed pumps
• in streams where flow occurs under the surface
• where the pools have become deeper or shallower.
• Where water extraction for stock and domestic use is high (e.g. in rural subdivisions surrounding large urban centres), The NSW Government may recommend actions to protect the environment in periods of no flow.
  

Water extraction and storage are high in dry times and impose long artificial droughts that increase the stress on aquatic plants and animals.

Measures to achieve objective

• Share low flows between the environment and water users and fully protect all very low natural flows.
• Very low flows: flows below the level naturally exceeded on 95% of all days with flow.
• Low flows: flows below the level naturally exceeded on 80% of all days with flow.
• Unless environmental, social and economic evaluations give an appropriate alternative, the following limits on water extraction apply:
• Environmental share in high-conservation-value streams: all very low flows and most of the low flows; no increase in extraction of low flows.
• Environmental share in other streams: all very low flows and 50-70% of daily low levels.
• New or transferred water licences should not allow extraction during low flows.
• In streams with little water use or important conservation values, minimise risks to ecosystems during low flows.
• Review management of town water supplies to assess whether changes may help achieve the objective without significantly affecting reliability.

Supporting information

• WSPs need to identify actions to achieve targets for each stream that balance local environmental, social or economic considerations.
• In streams where extraction currently exceeds 50% of low flow, WSPs may include provision to achieve targets. Where extraction is currently below 30% of low flow, it should not be allowed to exceed 30%.
• Augmentation of town water supplies to meet this objective will not be required. If augmentation for other reasons is proposed, appropriate levels of protection of low flows will be determined on a case-by-case basis.
• Where extraction for stock and domestic use is high (e.g. in rural subdivisions), WSPs may recommend appropriate actions to protect environmental values during low flows.
  

Rain causes peaks in river flows. This 'pulsing' of flows, including their duration, may trigger migration of animals and reproduction of plants and animals; provide over-bank flows to wetlands and floodplains; shape the river channel; and control water quality and nutrients. Water storage and extraction can alter or remove freshes, inhibiting these vital processes. The height, duration, season and frequency of higher flows are all important.

Measures to achieve objective

• Unless local information shows appropriate alternative targets, the following limits on extraction are recommended for use by RMCs.
  • No extraction of more than 30-50% of moderate to high flows on a daily basis (this means that for each stream the RMC should recommend an appropriate limit on the proportion of flows that may be extracted whenever flows are greater than the flows that would naturally be exceeded on 80% of all days with flow.For some streams the limit may be 30%; for other streams it may be as high as 50%.)
  • No increase in extractions in high-conservation streams.
• Where use exceeds the above limit, appropriate ways of limiting the volume or controlling the timing of extraction are needed.

Supporting information

• These targets are currently being met in many streams, particularly those with low water extraction.
• WSPs need to include appropriate actions to achieve this objective that balance environmental, economic or social considerations. RMCs may recommend variations from targets, if there is a demonstrated need.

Floodplain and wetland ecosystems develop in response to flow patterns and the nature of the landscape between the river and wetlands or floodplains. Floodplain works can change the flooding patterns, which will lead to changes in habitat and vegetation. These changes can be expected to result in reduced or different species diversity and abundance, particularly reduced numbers of native fish, and water quality problems.

Measures to achieve objective

• WSPs and actions need to include strategies to
  • maintain, restore or mimic natural patterns of inundation, water movement and drying in natural and semi-natural wetlands and remaining native floodplain ecosystems
  • ensure adequate access for native fish to and from floodplain wetlands
• Flooding patterns should not be altered without proper environment assessment.

Supporting information

• Property protection issues need to be taken into account.
  

Continuous or seasonal water releases from water storages, irrigation drainage or urban uses (e.g. overwatering gardens, effluent release) can mean streams and wetlands can sometimes be 'wetter' than natural. In streams and wetlands that naturally dry out, this can create problems in maintaining habitat, vegetation, nutrient cycling and signals for breeding. It can also lead to a high water table and associated salinity problems. Natural wetting and drying cycles produce diversity of habitat and, therefore, high species diversity.

Measures to achieve objective

• Identify any unregulated streams where unnatural flows have greatly reduced drying periods. Assess potential short- and long-term environmental, economic and social effects of this change and of possible management alternatives.
• Decisions on what, if any, action is appropriate to implement this objective in streams and wetlands should be worked out on a case-by-case basis after giving due consideration to local views. Where relevant, agreements under land and water management plans should be respected, but this objective should be taken into account, along with WQOs, social objectives and economic objectives, in resolving outstanding or new management issues for drainage water.

Supporting information

• This objective is being met in most streams.
  

Australia's rainfall and river flows are naturally variable. The way we currently store and divert river water can reduce natural pulsing of water down rivers and maintain artificially high or stable river heights. Hydroelectric releases can vary unnaturally between day and night. These changes often create problems with streambank stability, water quality, biodiversity and signals for breeding and migration.

Measures to achieve objective

• Identify streams with unnatural flow variability and develop actions to mimic natural variability.
• Identify streams with potential for flow variability problems and take early action.

Supporting information

• This objective applies mainly to controlled rivers but may apply in some locations or situations in uncontrolled streams.

Shutting off dam releases, or starting many pumps together, can drop river levels too quickly. If water levels fall too fast, water does not drain properly from riverbanks and they may collapse. Migration of aquatic animals may also be restricted by such sudden falls in river height. Very fast increases in flow and stream height can endanger people or aquatic animals and contribute to bank erosion.

Measures to achieve objective

• Identify locations where water levels often rise or fall faster than they would naturally. Identify the reasons and impacts. Remedial action requires case-by-case assessment.
• Identify potential problems and take early action.

Supporting information

• Unnatural rates of change are likely to occur only in streams with release or diversion works that have large capacity relative to the stream's normal flow.
• Local observations, such as bank erosion, may indicate a need for action.
• Solutions may involve slight changes to the operation of release valves, large pumps or diversion works.

Some shallow groundwaters are directly linked to flows in streams and wetlands. They may provide base flows in rivers during dry periods and may be primary sources of water for wetland, floodplain and riparian vegetation. Serious depletion of alluvial groundwater in dry times may lead to unnatural recharge of groundwater from surface waters during the next flow.

Measures to achieve objective

• Implement the State Groundwater Policy (DLWC 1997a, 1998b).
• Identify any streams or ecosystems that may depend on high groundwater levels and assess impacts of reduced recharge or excessive pumping.
• Identify where groundwaters may be rising and likely to threaten ecosystems or surface water quality.
• Determine appropriate action to keep groundwater level changes within acceptable bounds.

Supporting information

• River and groundwater management committees should identify areas and actions needed, particularly where there are threatened ecosystems.

Most instream structures (e.g. weirs) convert shallow flowing water to deep still water, thus altering habitat and increasing the risk of algal blooms or other water quality problems. Barriers restrict passage of plant propagules (e.g. seeds) and animals, particularly adult and juvenile fish.

Measures to achieve objective

• Implement the NSW Weirs Policy (DLWC 1997b).
• Identify and take action to improve fish passage on other structures that impede the two-way movement of native fish along streams or natural high-flow channels.

Supporting information

• The NSW Weirs Policy (DLWC 1997b) and weir review process will help set priorities and management options.

Many dams release water from the bottom of reservoirs where temperatures and dissolved oxygen are low and nutrient concentrations are high. These changed water quality conditions can affect the river downstream for hundreds of kilometres. For instance, many native fish will not breed in colder water. Some large weirs can adversely affect water quality for a short distance downstream.

Measures to achieve objective

• Determine whether water quality from dam releases limits achieving WQOs in unregulated streams and develop appropriate actions.

Supporting information

• WSPs only need to consider this objective in relation to those streams with large weirs or dams.

River systems can sometimes be affected by unforeseen or irregular events-such as algal blooms or the start of bird-breeding seasons. As river flows are a major determinant of many of these processes, we can sometimes alleviate a water quality or environmental problem by better managing river flows.

Measures to achieve objective

• Current water licence conditions enable pumping to be suspended in the rare event that this may be necessary. Release of some of the water in a dam for the downstream environment might be appropriate in particular circumstances. WSPs should identify potential situations when action may be warranted and the steps that should be taken to manage flows at these times.

Supporting information

• WSPs only need to consider this objective in relation to streams with significant water extraction or dams from which releases can be made.

This page was published 1 May 2006